The head of the U.N. refugee agency's local office, Laila Nassif said two boats carrying some 300 migrants capsized in the Red Sea. The official said another boat with 120 migrants overturned in the Arabian Sea.
Nassif said Saturday that about 110 people from the boats had been rescued. Yemen's official news agency reports Sunday that rescue efforts continue but that many people are still missing and feared to have drowned.
Each year, tens of thousands of Somalis and Ethiopians try to reach Yemen in hopes of escaping poverty or conflict in their homelands.
Hundreds die on the journey because of accidents and brutal treatment from smugglers.
Most of the ships cross the Gulf of Aden. The U.N. refugee agency says more than 50,000 people made the journey last year, and that at least 590 drowned trying.
Some information for this report was provided by AP.